High-nickel alloy powder, laser cladding transition layer, composite coating and preparation method and application of high-nickel alloy powder and laser cladding transition layer

Abstract

The invention belongs to the field of materials, and particularly provides high-nickel alloy powder, a laser cladding transition layer, a high-hardness, high-toughness and corrosion-resistant composite coating and preparation methods and application of the high-nickel alloy powder, the laser cladding transition layer and the composite coating. The high-nickel alloy powder is prepared from the following chemical components in percentage by mass: 0.8 percent to 1.8 percent of C, 0.5 percent to 2.0 percent of Si, 18.0 percent to 22.0 percent of Cr, 45.0 percent to 65.0 percent of Ni, 8.0 percent to 12.0 percent of Mo, 3.5 percent to 5.5 percent of Nb, 0.1 percent to 8.0 percent of Fe, 0.01 percent to 8.0 percent of W, 0.1 percent to 0.25 percent of N, 0 to 10 percent of Co and 0 to 1.0 percent of Mn. The laser cladding transition layer formed by the high-nickel alloy powder has excellent obdurability and interface bonding strength while ensuring high corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically providing a high-nickel alloy powder, a laser cladding transition layer, a high-hardness, high-toughness, and corrosion-resistant composite coating, and their respective preparation methods and applications. Background Technology

[0002] Laser cladding is a surface modification technology that uses a high-energy laser beam to simultaneously melt alloy powder and the surface of a substrate, forming a cladding coating that is metallurgically bonded to the substrate after rapid solidification. Due to the excellent wear and corrosion resistance of the resulting coating, this technology is currently used for surface strengthening and repair of key components in aerospace, energy, chemical, and marine engineering fields.

[0003] For extreme environments such as marine and chemical industries where chloride ion corrosion and wear coexist, critical components in marine equipment, such as hydraulic piston rods, ship propulsion shafts, and deep-sea valves, are not only exposed to high-concentration salt spray or seawater corrosion environments for extended periods, but also suffer from erosion and wear from sediment and suspended matter in seawater, as well as the impact risk from alternating loads. These harsh conditions place multiple demands on coating performance, requiring excellent salt spray corrosion resistance, high surface hardness, good impact toughness, and high adhesion strength to the substrate.

[0004] However, existing laser cladding coatings still face technical challenges in simultaneously achieving the aforementioned high corrosion resistance, high hardness, toughness, and high bonding strength. In the material design of high corrosion-resistant coatings, austenitic alloys with high chromium, nickel, and molybdenum content are typically used to ensure resistance to pitting corrosion in chloride ion environments. However, this sacrifices the coating's hardness and wear resistance to some extent, making it difficult to adapt to high-wear conditions. Conversely, adding large amounts of carbide-forming elements or introducing ceramic phases to increase hardness can improve wear resistance but may affect the coating's toughness and resistance to thermal cracking, leading to localized corrosion resistance decreases due to uneven microstructure, and even weakening the bonding strength between the coating and the substrate. Taking high-hardness ceramic coatings prepared by thermal spraying as an example, due to the significant differences in physical properties between ceramics and metal substrates, the interfacial bonding strength is often insufficient, and microcracks or spalling are easily generated due to thermal stress under the alternating hot and cold conditions of the marine environment. Furthermore, existing laser cladding coatings also suffer from problems such as high porosity and high crack sensitivity in the heat-affected zone in practical applications, further restricting their reliable application in high-end marine equipment. Given the unique characteristics of the marine environment, existing laser cladding coating materials typically require increasing the chromium and molybdenum content to improve pitting corrosion resistance. However, this approach often faces challenges such as increased alloy costs or a narrow process window, making it difficult to balance corrosion resistance, mechanical properties, and economic efficiency.

[0005] Therefore, it is necessary to develop a laser cladding coating material that can simultaneously meet multiple requirements such as salt spray corrosion resistance, high wear resistance, toughness and high bonding strength, in order to meet the stringent usage requirements of key components in marine, chemical and other fields under combined chloride ion corrosion and wear conditions. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, the present invention aims to provide a high-nickel alloy powder, a laser cladding transition layer, a high-hardness, high-toughness, and corrosion-resistant composite coating, as well as their respective preparation methods and applications. The laser cladding transition layer formed by the high-nickel alloy powder of this invention ensures high corrosion resistance while also possessing excellent toughness and interfacial bonding strength.

[0007] In a first aspect, the present invention provides a high-nickel alloy powder, wherein the chemical composition of the high-nickel alloy powder, by mass percentage, comprises: 0.8%~1.8% C, 0.5%~2.0% Si, 18.0%~22.0% Cr, 45.0%~65.0% Ni, 8.0%~12.0% Mo, 3.5%~5.5% Nb, 1.0%~8.0% Fe, 0.01%~8.0% W, 0.1%~0.25% N, 0~10% Co and 0~1.0% Mn.

[0008] In some embodiments of the present invention, the high-nickel alloy powder is formed by gas atomization of a mixture of raw materials including metal powder, carbon powder, single-crystal silicon powder and nitrogen-containing powder. The metal powder includes nickel powder, chromium powder, molybdenum powder, niobium powder, tungsten powder, iron powder and optional cobalt powder and optional manganese powder. The nitrogen-containing powder includes silicon nitride powder and / or nickel nitride powder.

[0009] In some embodiments of the present invention, the median particle size of the high-nickel alloy powder is 45~150μm.

[0010] In a second aspect, the present invention provides a laser cladding transition layer, which is formed by laser cladding process using the high-nickel alloy powder described in the first aspect of the present invention.

[0011] Thirdly, the present invention provides a method for preparing the laser cladding transition layer described in the second aspect of the present invention, comprising the following steps: (1) Provide the high-nickel alloy powder (2) Under the protection of inert gas, the high-nickel alloy powder is clad in multiple layers and multiple passes on the substrate using a laser to form a transition layer; (3) Anneal the transition layer.

[0012] The high-nickel alloy powder used in the laser cladding transition layer preparation of this invention is a high-nickel-chromium-molybdenum-niobium multi-element alloy system. On the one hand, Fe and Ni together form a continuously distributed austenitic matrix, ensuring high corrosion resistance while achieving good strength, toughness, and interfacial bonding strength. On the other hand, the coating formed by laser cladding has the characteristics of dense structure, fine grains, few defects, metallurgical bonding with the matrix, and extremely high bonding strength. Among them, the high Ni content endows the coating with excellent toughness and crack resistance, providing a foundation for the preparation of thick coatings, and synergistically stabilizes the austenitic matrix with Fe, avoiding the precipitation of brittle phases. The combination of Cr and Mo works synergistically in the austenitic matrix, significantly improving corrosion resistance, especially forming a stable and dense passivation film in chloride environments. The addition of Nb not only refines the microstructure, but more importantly, it preferentially forms fine NbC strengthening phases with C, improving strength while avoiding the formation of coarse and brittle carbides, thus overcoming the common problem of decreased toughness in high-hardness coatings due to carbide coarsening. In addition, Si plays a role in deoxidation and solid solution strengthening, improving the cladding processability. Building upon this foundation, the alloy system further incorporates N and W: N acts as a strong austenitic stabilizer, synergistically enhancing pitting corrosion resistance with Cr and Mo, resulting in a more dense and stable passivation film in chloride ion environments. This micro-alloying method achieves excellent salt spray corrosion resistance. W and Mo work synergistically in reducing media and chloride ion-containing composite environments, further strengthening the passivation film's stability. Simultaneously, W's incorporation into the solid solution or formation of fine carbides also contributes to increased strength. Through the multi-element synergistic effect of these elements, combined with high-nickel alloy powder and laser cladding technology, the transition layer composition system of this invention effectively overcomes the traditional coating contradiction of "high hardness equals poor corrosion resistance, and high corrosion resistance equals low hardness." Especially in harsh chloride environments such as marine and chemical plants, it achieves simultaneous improvement in corrosion resistance and hardness while maintaining the toughness of the austenitic matrix.

[0013] Fourthly, the present invention provides a high-hardness, high-toughness, and corrosion-resistant composite coating, comprising: a laser cladding transition layer formed on a substrate, and a high-hardness, wear-resistant functional layer disposed on the laser cladding transition layer, wherein the laser cladding transition layer is formed by laser cladding process using the high-nickel alloy powder described in the first aspect of the present invention.

[0014] In some embodiments of the present invention, the high-hardness wear-resistant functional layer is selected from one or more of type A, type B, and type C functional layers; wherein, the type A functional layer is an oxide ceramic layer or a composite material layer formed by a mixture of the high-nickel alloy powder and oxide ceramic powder; the type B functional layer is a carbide-based cermet layer or a composite material layer formed by a mixture of the high-nickel alloy powder and carbide-based cermet powder; and the type C functional layer is an electroplated hard chrome layer.

[0015] The composite coating of this invention employs a multi-layer structure design, in which a transition layer possesses both excellent toughness and corrosion resistance, forming a complementary combination system with the high-hardness, wear-resistant functional layer. As a "buffer layer" and "adhesive layer," the transition layer effectively alleviates the interfacial stress caused by the difference in physical properties between the high-hardness, wear-resistant functional layer and the substrate, significantly improving the bonding reliability between the functional layer and the substrate. Thus, layered optimization and synergistic enhancement of material properties are achieved, enabling the composite coating to possess high hardness, high wear resistance, high corrosion resistance, and good toughness.

[0016] Fifthly, the present invention provides a method for preparing the high-hardness, high-toughness, and corrosion-resistant composite coating as described in the fourth aspect of the present invention, comprising: forming the high-hardness and wear-resistant functional layer on the surface of the laser cladding transition layer.

[0017] In some embodiments of the present invention, the high-hardness and wear-resistant functional layer is selected from type A functional layer and / or type B functional layer, and the high-hardness and wear-resistant functional layer is formed by supersonic flame spraying or atmospheric plasma spraying.

[0018] In some embodiments of the present invention, the high-hardness wear-resistant functional layer is a C-type functional layer and is formed by an electroplating process.

[0019] In a sixth aspect, the present invention provides the application of the high-nickel alloy powder described in the first aspect, the laser cladding transition layer described in the second aspect, or the high-hardness, high-toughness, and corrosion-resistant composite coating described in the fourth aspect in marine engineering equipment or chlorine-containing chemical equipment.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 (a) to (d) are photographs taken after the laser cladding transition layer (based on 45# steel) of Preparation Example 1, Comparative Preparation Example 3, Comparative Preparation Example 2, and Comparative Preparation Example 1 was applied to the piston rod and subjected to an 8000-h neutral salt spray test. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] The "scope" disclosed in this invention is defined in the form of a lower limit and / or an upper limit, whereby a given scope is defined by selecting a lower limit and / or an upper limit. This scope may or may not include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form an undefined scope, and any lower limit can be combined with other lower limits to form an undefined scope, similarly, any upper limit can be combined with any other upper limit to form an undefined scope. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and can be combined with any other point or single value, or with other lower or upper limits, to form an undefined scope.

[0024] Unless otherwise specified, all embodiments and optional embodiments of the present invention may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0025] The first aspect of the present invention provides a high-nickel alloy powder, wherein the chemical composition of the high-nickel alloy powder, by mass percentage, comprises: 0.8%~1.8% C, 0.5%~2.0% Si, 18.0%~22.0% Cr, 45.0%~65.0% Ni, 8.0%~12.0% Mo, 3.5%~5.5% Nb, 1.0%~8.0% Fe, 0.01%~8.0% W, 0.1%~0.25% N, 0~10% Co and 0~1.0% Mn.

[0026] In some embodiments, the high-nickel alloy powder, by mass percentage, comprises: 0.8%~1.8% C, 0.5%~2.0% Si, 18.0%~22.0% Cr, 50.0%~62.0% Ni, 8.0%~12.0% Mo, 3.5%~5.5% Nb, 0.1%~5.0% Fe, 1.0%~8.0% W, 0.1%~0.25% N, 0~3.0% Co, and 0~1.0% Mn. As an example, the high-nickel alloy powder contains 0.01%~3.0% Co and / or 0.01%~1.0% Mn by mass percentage.

[0027] In some embodiments, the high-nickel alloy powder is formed by gas atomization of a mixture of raw materials including metal powder, carbon powder, single-crystal silicon powder, and nitrogen-containing powder. The metal powder includes nickel powder, chromium powder, molybdenum powder, niobium powder, tungsten powder, and iron powder, and the nitrogen-containing powder includes silicon nitride powder and / or nickel nitride powder. The mass percentage of nitrogen in the silicon nitride powder can be 30% to 40%, for example, 35%, 38.5%, 39.9%, etc., and the mass percentage of nitrogen in the nickel nitride powder can be 5% to 15%, for example, 7.3%, 11.0%, 12.0%, 13.5%, 14.0%, etc. Optionally, the metal powder also includes cobalt powder and / or manganese powder. Adding cobalt powder and / or manganese powder can improve the fluidity of the alloy melt, increase the stability of the atomization process and the powder yield, which is beneficial for obtaining high-nickel alloy powder with high sphericity and more uniform particle size distribution.

[0028] In this invention, the chemical composition of the high-nickel alloy powder can be a theoretical value calculated based on the amount of raw materials fed, with the sum of the mass percentages of each element being 100%. It is understood that in the actual preparation process, the raw materials used are all high-purity powders (purity ≥ 99.9%), and the finished product may contain trace amounts of unavoidable impurity elements from the raw materials, the total content of which is usually less than 0.1% and is ignored in the composition calculation.

[0029] As examples, the amounts of each raw material, by weight, are as follows: 50-62 parts nickel powder, 18-22 parts chromium powder, 8-15 parts molybdenum powder, 3.5-5 parts niobium powder, 1-8 parts tungsten powder, 0.1-5 parts iron powder, 0.8-1.8 parts carbon powder, 0.3-2.0 parts monocrystalline silicon powder, 0.4-2.1 parts nitrogen-containing powder (such as 0.7-2.1 parts nickel nitride powder or 0.4-1.0 parts silicon nitride powder), 0-10 parts cobalt powder, and 0-1 parts manganese powder. The total amount of each raw material can be 100-100.05 parts by weight.

[0030] In some embodiments, the median particle size (D50) of the high-nickel alloy powder is 45~150μm, for example 45μm, 50μm, 60μm, 80μm, 90μm, 110μm or 120μm.

[0031] A second aspect of the present invention provides a laser cladding transition layer, which is formed from the high-nickel alloy powder by a laser cladding process.

[0032] In this invention, the thickness of the laser cladding transition layer is determined based on the substrate material, the corrosion and wear level under operating conditions, and the design requirements of the composite coating. As some examples, the thickness of the laser cladding transition layer can be 0.5~3mm, such as 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, or 2.5mm.

[0033] A third aspect of the present invention provides a method for preparing the laser cladding transition layer described in the second aspect of the present invention, the method comprising the following steps: (1) Provide the high-nickel alloy powder; (2) Under the protection of inert gas, the spherical high-nickel alloy powder is clad in multiple layers and multiple passes on the substrate using a laser to form a transition layer; (3) Anneal the transition layer.

[0034] According to some specific implementation methods, step (1) includes: (1-1) The raw materials, including metal powder, carbon powder, single crystal silicon powder and nitrogen-containing powder, are mixed evenly to obtain a raw material mixture; wherein the metal powder includes nickel powder, chromium powder, molybdenum powder, niobium powder, tungsten powder, iron powder and optional cobalt powder and optional manganese powder, and the nitrogen-containing powder is silicon nitride powder and / or nickel nitride powder. (1-2) The raw material mixture is atomized to produce spherical high-nickel alloy powder.

[0035] In step (1-1), the raw materials are described as described in the first aspect of the present invention, and will not be repeated here.

[0036] In steps (1-2), the high-nickel alloy powder prepared by the gas atomization powder preparation process can be spherical alloy powder. As some examples, the operating conditions for the gas atomization powder preparation include: heating and melting the raw material mixture at a melting temperature of 1550~1650℃, such as 1550℃, 1560℃, 1580℃, 1600℃, 1650℃, etc.; using a high-pressure inert gas (such as argon) as the atomization medium at an atomization pressure of 4~6MPa, such as 4MPa, 4.5MPa, 5MPa, 6MPa, etc.; and sieving the atomized powder to obtain spherical high-nickel alloy powder.

[0037] In step (2), the substrate can be selected from carbon steel, alloy steel, stainless steel or cast iron, such as 45# steel. Preferably, the substrate is pretreated before cladding: the surface of the substrate to be clad is finely ground or sandblasted to remove oxide scale and rust, then cleaned and degreased with acetone or alcohol, and dried for later use.

[0038] In step (2), the multi-layer multi-pass cladding refers to the sequential deposition of multiple cladding layers on the substrate surface by laser cladding, each layer consisting of multiple overlapping cladding passes; after completing one cladding layer, the next cladding layer is continued on the surface of the deposited cladding layer until the required total thickness is achieved.

[0039] In some embodiments, the operating conditions for the multi-layer, multi-pass cladding include: laser power of 2.5~4.0kW, scanning speed of 5~12mm / s, spot diameter of 2~4mm, overlap rate of 35%~50%, and powder feed rate of 20~35g / min. Under these process conditions, a transition layer with higher density, no cracks, and better bonding performance with the substrate can be obtained.

[0040] In step (3), the transition layer is annealed to release residual stress caused by the difference in crystal structure and thermal expansion coefficient between the transition layer and the substrate during deposition, and to repair microscopic defects. Preferably, the annealing temperature is 550~650℃ and the time is 1~2h.

[0041] A fourth aspect of the present invention provides a high-hardness, high-toughness, and corrosion-resistant composite coating, comprising: a laser cladding transition layer formed on a substrate, and a high-hardness, wear-resistant functional layer disposed on the laser cladding transition layer. The laser cladding transition layer is prepared from the high-nickel alloy powder described in the first aspect of the present invention via a laser cladding process. The description and preparation method of the laser cladding transition layer are as described in the second and third aspects, respectively, and will not be repeated here.

[0042] In this invention, the material of the high-hardness, wear-resistant functional layer can be selected according to the working conditions, and may include, but is not limited to, ceramics, cermets, or high-hardness metals. The transition layer of this invention has excellent corrosion resistance, toughness, and interfacial bonding performance, and can provide a reliable supporting substrate for functional layers of different materials. While ensuring the high hardness of the coating, it effectively alleviates the interfacial stress caused by the difference in physical properties between the functional layer and the substrate, thereby improving the service reliability of the composite coating.

[0043] In some embodiments, the high-hardness wear-resistant functional layer is selected from one or more of type A, type B, and type C functional layers.

[0044] [Type A Functional Layer] The Type A functional layer is an oxide ceramic layer, or a composite material layer formed by a mixture of the high-nickel alloy powder and oxide ceramic powder. This type of coating provides excellent wear resistance, corrosion resistance, and insulation properties, while also possessing high-temperature oxidation resistance and media compatibility. It is particularly suitable for components in marine / chemical fields subjected to coupled high-temperature oxidation, corrosion, and wear conditions, such as deep-sea high-temperature valves, chemical sealing rings, roller surfaces of seawater desalination plants, and linings of chlorination reactors.

[0045] In the type A functional layer, the oxide ceramic can be selected from one of Cr2O3, Al2O3, and TiO2, or a composite oxide formed from two or more of them. As a preferred example, the composite oxide is formed from Al2O3 and TiO2, and the mass percentage of TiO2 can be 10% to 15%, for example, 10%, 13%, or 15%. The addition of an appropriate amount of TiO2 helps to improve the density and toughness of the coating.

[0046] The thickness of the type A functional layer can be selected according to the wear and corrosion resistance requirements under operating conditions. As some embodiments, the thickness of the type A functional layer is 50~300μm, for example 50μm, 80μm, 100μm, 150μm, 200μm or 280μm.

[0047] [Type B Functional Layer] The Type B functional layer is a carbide-based cermet layer, or a composite material layer formed by a mixture of high-nickel alloy powder and carbide-based cermet powder. This type of coating has extremely high hardness, excellent wear resistance, and good toughness, making it suitable for harsh working conditions with strong abrasion and high concentrations of chlorine media. It is particularly suitable for components in marine engineering and chlorination-containing industrial fields that are subject to erosion by solid particles, such as flow parts of marine slurry pumps, elbows in oil and gas mixed-transport pipelines, deep-sea drilling tools, chlor-alkali industry slurry conveying pipelines, and hydrocyclones in chlorination process titanium dioxide production units.

[0048] The carbide-based cermet in the B-type functional layer refers to a composite material formed by using carbides as the hard phase and metal (including alloys) as the binder phase. By mass percentage, the proportion of the metal binder phase is usually 10% to 40% to ensure that the hard phase has tough support while obtaining high hardness.

[0049] In some embodiments, the carbide-based cermet is selected from at least one of WC-Co, WC-CoCr, and Cr3C2-NiCr.

[0050] The thickness of the type B functional layer can be selected according to the erosion and wear intensity under operating conditions, the corrosion level of the medium, and the service life requirements of the component. As some embodiments, the thickness of the type B functional layer is 100~500μm, for example 120μm, 150μm, 200μm, 240μm, 300μm, 330μm or 450μm.

[0051] As described above, both the Type A and Type B functional layers can selectively contain the high-nickel alloy powder of the present invention. In some cases, due to the difference in thermal expansion coefficients between oxide ceramics, carbide-based cermets (hereinafter collectively referred to as "ceramic materials") and different matrices, direct bonding can easily generate thermal stress at the interface. Introducing the high-nickel alloy powder can gradient the difference in thermal expansion coefficients, alleviate interfacial thermal stress, and thus improve the bonding performance. The specific amount of the high-nickel alloy powder can be selected according to the type of ceramic material and the matrix. Typically, in a mixture composed of high-nickel alloy powder and ceramic materials, the mass percentage of the high-nickel alloy powder can be controlled between 2% and 50%. Furthermore, the composite material layer can be prepared by uniformly mixing high-nickel alloy powder and ceramic powder materials and then using a supersonic flame spraying process or an atmospheric plasma spraying process to form a functional layer, in order to further optimize the interfacial bonding effect.

[0052] [C-type functional layer] The C-type functional layer is an electroplated hard chrome layer, which has high hardness, good wear resistance, and excellent corrosion resistance, and is relatively low in cost. It is suitable for chlorine media conditions with high dimensional accuracy requirements, moderate wear, and no strong erosion. This type of coating is particularly suitable for precision transmission components in marine engineering and chlorine-containing chemical fields, such as hydraulic piston rods for marine equipment, precision shafts for chemical pumps, plungers for metering pumps in the chlor-alkali industry, valve stems for deep-sea valves, and precision working surfaces of mold cavities.

[0053] The thickness of the C-type functional layer is determined based on the component's dimensional accuracy requirements, the intensity of moderate wear conditions, and the need for resistance to chloride ion corrosion. In some embodiments, the thickness of the C-type functional layer is 20~200μm, for example, 20μm, 50μm, 60μm, 100μm, 140μm, 170μm, or 190μm.

[0054] In some embodiments, the performance indicators of the composite coating are as follows: surface hardness ≥800HV0.3, salt spray corrosion resistance time ≥8000h without red rust, bonding strength ≥55MPa, no peeling when bent at 30°, elongation at break ≥10.8%, possessing both high hardness, excellent corrosion resistance and high strength and toughness.

[0055] A fifth aspect of the present invention provides a method for preparing the high-hardness, high-toughness, and corrosion-resistant composite coating, comprising: forming the high-hardness, wear-resistant functional layer on the surface of the laser cladding transition layer. The specific forming process of the high-hardness, wear-resistant functional layer can be selected according to the type of functional layer.

[0056] For both Type A and Type B functional layers, supersonic flame spraying or atmospheric plasma spraying (APS) processes can be used for preparation. Typically, before forming the functional layers, the preparation method may further include sandblasting to roughen the surface of the transition layer, thereby increasing the mechanical interlocking area of ​​the subsequent functional layers. Preferably, supersonic flame spraying is used to prepare the Type B functional layer. This further improves the coating density and bonding strength.

[0057] In some embodiments, the operating conditions for supersonic flame spraying include: using kerosene or natural gas as fuel, and controlling the oxygen flow rate at 800-1000 L / min. Further, the spraying distance for supersonic flame spraying can be 300-400 mm, and the powder feed rate can be 40-80 g / min.

[0058] In some embodiments, the operating conditions for atmospheric plasma spraying include: current 450~650A, power 35~45kW, main gas flow rate 35~50L / min, auxiliary gas flow rate 5~12L / min, powder feeding rate 20~35g / min, and spraying distance 80~120mm.

[0059] For the C-type functional layer, electroplating is used for preparation. Before electroplating, the surface of the transition layer can be activated to ensure good adhesion between the plating layer and the transition layer. As an example, the activation treatment may include the following steps: first, dry polishing the surface of the cladding transition layer with 400-600 grit metallographic sandpaper to remove micro-protrusions, slag, and loose layers, obtaining a smooth and uniform substrate surface (roughness Ra controlled at 0.8-1.6 μm); then, electrochemical degreasing is performed by cathodic electrolysis at 60-80°C for 3-8 minutes in an alkaline solution containing 50-80 g / L sodium hydroxide and 20-35 g / L sodium carbonate to remove surface oil; after degreasing, the surface is washed with hot water and then immersed in a 10%-20% dilute sulfuric acid solution at room temperature for 30-60 seconds to remove any oxide film that may be present on the surface.

[0060] The preparation method provided by this invention constructs a gradient preparation process system adapted to the needs of different functional layers through the synergistic integration of laser cladding, thermal spraying, and electroplating technologies. Specifically, firstly, a laser cladding process is used to prepare the transition layer described in the first aspect of this invention on the substrate surface. This process optimizes process parameters such as laser power, scanning speed, and overlap rate to ensure that the transition layer has a dense structure, is free of cracks and defects, and forms a reliable metallurgical bonding interface with the substrate. As some embodiments, according to the surface performance requirements of preset working conditions, type A, type B, or type C high-hardness wear-resistant functional layers are prepared on the surface of the transition layer. Among them, type A and type B functional layers are deposited using supersonic flame spraying or atmospheric plasma spraying processes. Before spraying, the surface of the transition layer is roughened by sandblasting, and the interface morphology conducive to mechanical interlocking is obtained by controlling the roughness parameters to enhance the bonding strength between the functional layer and the transition layer; the type C high-hardness wear-resistant functional layer is prepared by electroplating, and the surface of the transition layer is activated before plating to improve the electrochemical deposition conditions. The preparation process system is designed based on the physicochemical properties of each process and the compatibility of the transition layer material, realizing the construction of gradient performance from the bottom transition layer to the surface functional layer.

[0061] The sixth aspect of the present invention provides the application of the high-nickel alloy powder, the laser cladding transition layer, or the high-hardness, high-toughness, and corrosion-resistant composite coating in marine engineering equipment or chlorine-containing chemical equipment.

[0062] As described above, the laser cladding transition layer and composite coating of the present invention have excellent corrosion resistance, high hardness and good toughness, and are especially suitable for harsh service environments with high concentration of chloride ions, high wear and alternating stress coupling.

[0063] In this invention, the marine engineering equipment includes, but is not limited to, key structural components of deep-sea oil production platforms (e.g., manifolds, connectors), flow components of seawater desalination devices (e.g., high-pressure pumps, flash tanks), subsea pipeline systems, ship propulsion systems (e.g., propellers, stern shafts), seawater pumps and valves, and hydraulic transmission components (e.g., piston rods).

[0064] In this invention, the chlorine-containing chemical equipment includes, but is not limited to, chlor-alkali industrial electrolytic cells (e.g., ion-exchange membrane electrolytic cells, chlorine coolers), chlorination process production reactors, chlorine-containing organic synthesis equipment and related components.

[0065] The following describes embodiments of the present invention. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0066] In the following preparation examples and comparative examples, the N element content of the silicon nitride powder used was 38.5% by mass. Unless otherwise stated, all parts refer to parts by mass.

[0067] Preparation Example 1: Preparation of the transition layer (1) Provide high-nickel alloy powder Mix 58.00 parts of nickel powder, 20.50 parts of chromium powder, 10.50 parts of molybdenum powder, 4.50 parts of niobium powder, 2.00 parts of tungsten powder, 2.12 parts of iron powder, 0.68 parts of monocrystalline silicon powder, 1.20 parts of carbon powder, and 0.52 parts of silicon nitride powder evenly to obtain a raw material mixture.

[0068] The above-mentioned raw material mixture was loaded into a vacuum induction melting gas atomization device, a vacuum was drawn, and then, under argon protection, the temperature was raised to 1560℃ and held for 30 minutes to ensure the raw materials were fully and uniformly melted. The melt temperature was adjusted to 1500℃, and the melt flowed out through a 3.5mm diameter nozzle, atomized with 4.3MPa high-pressure argon gas. The atomized droplets cooled and solidified into spherical powder as they flew within the tower. After cooling to room temperature under argon protection, the powder was removed, vibrated, and sieved to obtain alloy powder with a D50 of 90μm for later use.

[0069] (2) Melt spraying 45# steel was selected as the base material. The surface oxide layer was removed by sandblasting, and the material was ultrasonically cleaned with ethanol and then dried. The laser cladding process parameters were as follows: laser power 3.2kW, scanning speed 24mm / s, spot diameter 3mm, overlap rate 50%, powder feeding rate 12g / min, protective gas flow rate 15L / min, and carrier gas flow rate 6L / min.

[0070] Perform multi-layer, multi-pass cladding according to the above parameters: First, perform the first multi-pass cladding on the substrate surface with an overlap spacing of 1.5mm. After multiple scans, cover the substrate surface to obtain a cladding layer with a thickness of about 0.4mm. After the first cladding is completed, perform the second cladding with the same process parameters, with the scanning direction perpendicular to the previous layer. Repeat this process for a total of 3 cladding layers to obtain a transition layer with a thickness of about 1.2mm, denoted as M1.

[0071] Preparation Example 2 The transition layer was prepared according to the method of Preparation Example 1, except that cobalt powder was added in step (1). Specifically, cobalt powder was added in step (1). Specifically, 55.0 parts of nickel powder, 19.0 parts of chromium powder, 9.5 parts of molybdenum powder, 4.0 parts of niobium powder, 6.0 parts of tungsten powder, 2.0 parts of cobalt powder, 1.6 parts of iron powder, 0.88 parts of single crystal silicon powder, 1.5 parts of carbon powder, and 0.52 parts of silicon nitride powder were mixed evenly and formed into spherical high-nickel alloy powder by gas atomization.

[0072] The remaining steps are the same as in Preparation Example 1, and the resulting transition layer is denoted as M2.

[0073] Preparation Example 3 The transition layer was prepared according to the method of Preparation Example 1, except that manganese powder was added in step (1). Specifically, 59.00 parts of nickel powder, 21.00 parts of chromium powder, 11.00 parts of molybdenum powder, 5.00 parts of niobium powder, 1.50 parts of tungsten powder, 0.10 parts of iron powder, 0.50 parts of manganese powder, 0.64 parts of single crystal silicon powder, 1.00 parts of carbon powder, and 0.26 parts of silicon nitride powder were mixed evenly and formed into spherical high-nickel alloy powder by gas atomization powder preparation.

[0074] The remaining steps are the same as in Preparation Example 1, and the resulting transition layer is denoted as M3.

[0075] Comparative Preparation Example 1 The transition layer was prepared according to the method of Preparation Example 1, except that in step (1), niobium powder, silicon nitride powder and tungsten powder were not used. Specifically, 62.0 parts of nickel powder, 13.0 parts of chromium powder, 1.5 parts of molybdenum powder, 22.7 parts of iron powder, 0.5 parts of single crystal silicon powder and 0.3 parts of carbon powder were mixed evenly and formed into spherical high-nickel alloy powder by gas atomization powder preparation.

[0076] The remaining steps are the same as in Preparation Example 1, and the resulting transition layer is denoted as D1.

[0077] Comparative Preparation Example 2 The transition layer was prepared according to the method of Preparation Example 1. The difference is that in step (1), silicon nitride powder and tungsten powder were not used. Specifically, 50.0 parts of nickel powder, 19.0 parts of chromium powder, 9.0 parts of molybdenum powder, 4.0 parts of niobium powder, 8.0 parts of cobalt powder, 7.7 parts of iron powder, 0.8 parts of single crystal silicon powder, and 1.5 parts of carbon powder were mixed evenly and formed into spherical high-nickel alloy powder by gas atomization powder preparation.

[0078] The remaining steps are the same as in Preparation Example 1, and the resulting transition layer is denoted as D2.

[0079] Comparative preparation example 3 The transition layer was prepared according to the method of Preparation Example 1. The difference is that in step (1), silicon nitride powder was not used. Specifically, 55.5 parts of nickel powder, 20.0 parts of chromium powder, 10.5 parts of molybdenum powder, 4.5 parts of niobium powder, 5.5 parts of iron powder, 1.0 part of single crystal silicon powder, 1.0 part of carbon powder, and 2.0 parts of tungsten powder were mixed evenly and formed into spherical high-nickel alloy powder material by gas atomization powder preparation.

[0080] The remaining steps are the same as in Preparation Example 1, and the resulting transition layer is denoted as D3.

[0081] The chemical compositions of the high-nickel alloy powders prepared in the above examples and comparative examples are shown in Table 1.

[0082] Table 1

[0083] Example 1: M1+B type composite coating The transition layer M1 of Preparation Example 1 was roughened by sandblasting (Al2O3 sand, particle size 24 mesh, the same below), and commercial WC-10Co4Cr powder (particle size 15~45μm, purchased from Tianjin Bohai Welding Materials Co., Ltd., grade ZJ338) was sprayed using an HVOF spraying equipment (fuel is kerosene, oxygen flow rate is 900L / min, spraying distance is 350mm, powder feed rate is 60 g / min) to achieve a coating thickness of about 200μm.

[0084] Example 2: M1+A type composite coating The transition layer M1 from Preparation Example 1 was roughened by sandblasting, and Al2O3-13%TiO2 composite powder (particle size 15~45μm, purchased from Zhengzhou Feisuo Nanotechnology Co., Ltd., grade ATO13) was sprayed using an APS spraying equipment. The spraying parameters were: current 550A, power 40kW, main gas Ar flow rate 40L / min, auxiliary gas H2 flow rate 8L / min, powder feed rate 25g / min, and spraying distance 100mm. Multiple spraying passes were used to achieve a coating thickness of approximately 150μm.

[0085] Example 3: M1+C type composite coating The pretreatment before electroplating includes degreasing and activation: First, the surface of the cladding transition layer is dry-polished with 400-mesh and 600-mesh metallographic sandpaper to remove micro-protrusions, slag and loose layer on the surface of the cladding layer, so as to obtain a smooth and uniform substrate surface (roughness Ra about 1.2μm); then, electrochemical degreasing is performed by cathodic electrolysis at 70℃ for 5 minutes in an alkaline solution containing 60g / L NaOH and 25g / L Na2CO3 to remove oil stains; after degreasing, it is rinsed with hot water and then immersed in 15% dilute sulfuric acid solution at room temperature for 45s to remove the surface oxide film. After activation, it is immediately rinsed with water and transferred to the plating tank.

[0086] The hard chrome electroplating process uses a plating solution of 220 g / L chromic anhydride and 2.2 g / L sulfuric acid, at a temperature of 55℃, and a cathode current density of 45 A / dm³. 2 The workpiece is lowered into the tank while energized; for the first 30 seconds, an 80A / dm² voltage is applied. 2 The inrush current was applied, followed by normal electroplating for 35 minutes to achieve a thickness of 50 μm.

[0087] Comparative Example 1: D3+B type composite coating The composite coating was prepared according to the method of Example 1, except that the transition layer M1 was replaced with D3.

[0088] Comparative Example 2: D3+A type composite coating The composite coating was prepared according to the method of Example 2, except that the transition layer M1 was replaced with D3.

[0089] Comparative Example 3: D3+C type composite coating The composite coating was prepared according to the method of Example 3, except that the transition layer M1 was replaced with D3.

[0090] Test case This test example is used to evaluate the performance of the above transition layer and composite coating. The specific test methods and conditions are as follows: 1. Hardness test The test was conducted according to GB / T 4340.1, using a Vickers hardness tester with a test force of 2.942 N (HV0.3) and a holding time of 15 s. Points were marked every 0.1 mm along the coating cross-section from the surface to the substrate, with five measurements taken at each location and the average value recorded.

[0091] 2. Bond strength Performed according to ASTM C633, using cylindrical specimens (φ25mm × 25mm). The coated surfaces were bonded to the mating parts using adhesive (FM-1000). After curing, tensile tests were performed on a universal testing machine at a loading rate of 1mm / min. The breaking load was recorded. The bond strength was calculated as the breaking load divided by the bond area. The average value of 5 specimens in each group was taken.

[0092] 3. Tensile strength, yield strength, and elongation at break According to GB / T 228.1, the coated substrate is processed into plate-shaped tensile specimens (original gauge length 50 mm, thickness 2 mm, coating retained on the surface), the test temperature is 25℃, the tensile rate is 2 mm / min, and the tensile strength, specified plastic extension strength and elongation after fracture are determined. The average value of 3 specimens in each group is taken.

[0093] 4. Bending performance Three-point bending test was conducted according to GB / T 232. The sample size was 100 mm × 25 mm × 2 mm (coating facing outwards). A 60 mm span and a 5 mm indenter radius were used. The load was applied at a rate of 2 mm / min until the bending angle reached 30°, and then unloaded. The surface of the coating in the bending area was observed for cracks, peeling, or hairline marks.

[0094] 5. Wear resistance Dry abrasive wear tests were conducted according to ASTM G65, with a load of 130 N, a rubber wheel speed of 200 r / min, abrasive material of quartz sand (50-70 mesh), a flow rate of 300 g / min, and a total rotation speed of 6000 rpm. Wear resistance was evaluated by wear volume or mass loss, and the average value of 3 samples in each group was taken.

[0095] 6. Corrosion resistance A 45# cylindrical piston rod (90mm in diameter and 900mm in length) with a transition layer was subjected to a neutral salt spray test (NSS) according to GB / T 10125. The test solution was a 5% NaCl solution (pH 6.5~7.2), the spray chamber temperature was 35℃, and the spraying was continuous for 8000 h. The corrosion status of the sample surface was observed every 24 h, and the time and area of ​​rust spots were recorded.

[0096] The test results of the substrate samples with transition layers and composite coatings are shown in Tables 2 and 3, respectively.

[0097] Table 2

[0098] As shown in Table 2, compared with Comparative Preparation Examples 1-3, the laser cladding transition layers prepared in Preparation Examples 1-3 exhibit superior surface hardness (610-675 HV0.3), tensile strength (705-742 MPa), yield strength (470-510 MPa), elongation after fracture (11.8%-15.5%), and flexural properties (no cracks at 30°). Furthermore, the wear loss (180-240 mg) is significantly lower than that of Comparative Preparation Examples 1-3 (260-320 mg). Regarding corrosion resistance, Preparation Examples 1-3 showed no red rust after 8000 hours of neutral salt spray testing, while Comparative Preparation Examples 1-3 showed red rust after 3200 hours, 4500 hours, and 6000 hours, respectively. This indicates that they simultaneously possess high strength, good plasticity, excellent wear resistance, and corrosion resistance.

[0099] In addition, combined Figure 1 It can be seen that after 8000h of neutral salt spray test, no red rust appeared on the piston rod corresponding to the sample of Preparation Example 1, while the piston rods corresponding to the comparative preparation examples 1 to 3 showed different degrees of red rust, and the sample of comparative preparation example 1 had the most severe corrosion.

[0100] As shown in Tables 1 and 2, compared with Comparative Preparation Examples 1-3, Preparation Examples 1-3 introduced core elements such as C, N, W, and Nb into their composition, forming a synergistic ratio with Cr, Ni, and Mo: C forms a stable carbide reinforcing phase with Nb and W, significantly improving hardness and wear resistance; N synergistically enhances passivation ability with Cr, Mo, and Ni, greatly improving corrosion resistance; W and Nb further refine the microstructure, improving the strength-toughness balance. In contrast, Comparative Preparation Examples 1-3, lacking the synergistic effect of the aforementioned core elements, exhibited problems such as insufficient hardness, poor wear resistance, or deteriorated corrosion resistance.

[0101] Table 3

[0102] As shown in Tables 2 and 3, the transition layer M1 in Preparation Example 1 exhibits excellent overall performance balance. Its hardness is 675 HV0.3, its bonding strength with the substrate is as high as 83 MPa, its elongation after fracture is 15.5%, it shows no cracking during bending, and it shows no red rust after 8000 hours of NSS testing, providing a guarantee for its role as the "foundation" of the composite coating. Based on this, the composite coating constructed using the transition layer M1 exhibits even better overall performance. Specifically, the surface hardness of Example 1 (M1+B type, WC-CoCr) jumps to 1250 HV0.3, and the wear loss is significantly reduced to 45 mg, while maintaining the excellent corrosion resistance (no red rust after 8000 hours of NSS testing) and good overall toughness (14.1% elongation after fracture, no peeling during bending) imparted by the transition layer. The bonding strength between the composite coating and the substrate remains as high as 83 MPa. Examples 2 (M1+A type) and 3 (M1+C type) also achieved surface hardness of 1050HV0.3 and 850HV0.3, respectively, with wear loss of 65mg and 95mg, and inherited the corrosion resistance of transition layer M1. The bonding strength between the composite coating and the substrate was 81MPa and 74MPa, respectively. Compared with transition layer M1, the main failure mode of all composite coatings was improved to "slight surface wear", successfully achieving a balance between high hardness, high wear resistance, high corrosion resistance, and good toughness.

[0103] In contrast, with the same surface layer type, the composite coatings (Comparative Examples 1-3) constructed based on the transition layer D3 of Comparative Preparation Example 3 all received a "poor" overall performance evaluation. Taking Comparative Example 1 (D3+B type) as an example, although its surface hardness reached 1220HV0.3, the bonding strength between the composite coating and the substrate was only 71MPa, the elongation after fracture was only 8.5%, slight hairline cracking appeared during bending, red rust appeared after only 2800h in the NSS test, and the wear loss reached 60mg. The main failure modes were coating hairline cracking and substrate corrosion. Comparative Examples 2 (D3+A type) and 3 (D3+C type) also had problems such as low bonding strength, poor plasticity, and insufficient corrosion resistance, and their overall performance evaluation was also "poor". The above comparisons further indicate that the transition layer D3 itself has poor strength and toughness matching and insufficient corrosion resistance. Even with different surface layer types, it is still difficult to obtain ideal overall performance.

[0104] It is evident that the excellent strength-toughness matching and corrosion resistance of the transition layer M1 are the key foundation for the composite coating to achieve high overall performance.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A high-nickel alloy powder, characterized in that, The chemical composition of the high-nickel alloy powder, by mass percentage, includes: 0.8%~1.8% C, 0.5%~2.0% Si, 18.0%~22.0% Cr, 45.0%~65.0% Ni, 8.0%~12.0% Mo, 3.5%~5.5% Nb, 0.1%~8.0% Fe, 0.01%~8.0% W, 0.1%~0.25% N, 0~10% Co and 0~1.0% Mn.

2. The high-nickel alloy powder according to claim 1, characterized in that, The high-nickel alloy powder is formed by gas atomization of a mixture of raw materials including metal powder, carbon powder, single-crystal silicon powder and nitrogen-containing powder. The metal powder includes nickel powder, chromium powder, molybdenum powder, niobium powder, tungsten powder, iron powder and optional cobalt powder and optional manganese powder. The nitrogen-containing powder is silicon nitride powder and / or nickel nitride powder. Preferably, the median particle size of the high-nickel alloy powder is 45~150μm.

3. A laser cladding transition layer, characterized in that, The high-nickel alloy powder described in claim 1 or 2 is prepared by laser cladding process; Preferably, the thickness of the laser cladding transition layer is 0.5~3mm.

4. A method for preparing the laser cladding transition layer according to claim 3, characterized in that, Includes the following steps: (1) Provide the high-nickel alloy powder; (2) Under the protection of inert gas, the high-nickel alloy powder is clad in multiple layers and multiple passes on the substrate using a laser to form a transition layer; (3) Anneal the transition layer.

5. The method according to claim 4, characterized in that, Step (1) includes: (1-1) The raw materials, including metal powder, carbon powder, single crystal silicon powder and nitrogen-containing powder, are mixed evenly to obtain a raw material mixture; wherein the metal powder includes nickel powder, chromium powder, molybdenum powder, niobium powder, tungsten powder, iron powder and optional cobalt powder and optional manganese powder, and the nitrogen-containing powder is silicon nitride powder and / or nickel nitride powder. (1-2) The raw material mixture is atomized to obtain spherical high-nickel alloy powder; Preferably, in step (2), the operating conditions for the multi-layer multi-pass cladding include: laser power of 2.5~4.0kW, scanning speed of 5~12mm / s, spot diameter of 2~4mm, overlap rate of 35%~50%, and powder feeding rate of 20~35g / min; Preferably, in step (3), the annealing conditions include a temperature of 550~650℃ and a time of 1~2h.

6. A high-hardness, high-toughness, and corrosion-resistant composite coating, characterized in that, include: A laser cladding transition layer formed on a substrate, and a high-hardness, wear-resistant functional layer disposed on the laser cladding transition layer, wherein the laser cladding transition layer is formed by laser cladding process using the high-nickel alloy powder described in claim 1 or 2.

7. The high-hardness, high-toughness, and corrosion-resistant composite coating according to claim 6, characterized in that, The high-hardness, wear-resistant functional layer is selected from one or more of type A, type B, and type C functional layers; wherein... The type A functional layer is an oxide ceramic layer or a composite material layer formed by a mixture of high-nickel alloy powder and oxide ceramic powder as described in claim 1 or 2; The type B functional layer is a carbide-based metal ceramic layer or a composite material layer formed by a mixture of high-nickel alloy powder and carbide-based metal ceramic powder as described in claim 1 or 2. The C-type functional layer is an electroplated hard chrome layer.

8. The high-hardness, high-toughness, and corrosion-resistant composite coating according to claim 7, characterized in that, The oxide ceramic in the type A functional layer is selected from one of Cr2O3, Al2O3, and TiO2, or is a composite oxide formed from two or more of them; Preferably, in the type A functional layer, the composite oxide is composed of Al2O3 and TiO2, and the mass percentage of TiO2 is 10%~15%. Preferably, the thickness of the type A functional layer is 50~300μm; Preferably, the carbide-based cermet in the type B functional layer is selected from at least one of WC-Co, WC-CoCr, and Cr3C2-NiCr; Preferably, the thickness of the type B functional layer is 100~500μm; Preferably, the thickness of the C-type functional layer is 20~200μm.

9. A method for preparing a high-hardness, high-toughness, and corrosion-resistant composite coating according to any one of claims 6-8, characterized in that, include: The high-hardness, wear-resistant functional layer is formed on the surface of the laser cladding transition layer; Preferably, the high-hardness, wear-resistant functional layer is a type A functional layer and / or a type B functional layer, and the high-hardness, wear-resistant functional layer is formed using a supersonic flame spraying process or an atmospheric plasma spraying process; or, The high-hardness and wear-resistant functional layer is a C-type functional layer and is formed by electroplating. Preferably, the operating conditions of the supersonic flame spraying process include: using kerosene or gas as fuel, and an oxygen flow rate of 800~1000L / min.

10. The application of the high-nickel alloy powder of claim 1 or 2, the laser cladding transition layer of claim 3, or the high-hardness, high-toughness, and corrosion-resistant composite coating of any one of claims 6-8 in marine engineering equipment or chlorine-containing chemical equipment.

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